The purpose of this project is to get clinical and pathologic materials from patients with retinal dysfunctions and to study the effects of graded doses of sunlight on the foveas of human volunteers. The investigator will also continue to carry out a histopathologic study of fluorescein angiography in human patients who have various retinopathies. The investigators will also study the choriocapillaries from patients with ischemic diseases of the retina and choroid with flat preparations. Attempts to produce experimental models of macular edema in rhesus monkeys will be continued. The investigators will observe the effects of delayed degeneration of retina in rhesus monkeys after damage by laser or white light 2-3 years ago. Therefore, our overall objective is to study patients with retinal dysfunctions at clinical, microscopic and ultrastructural levels and to create experimental models in animals to examine the pathogenetic mechanisms.